7.5 Bubble Quality

Bubble content is determined by taking a sample of glass from each melt. The total bubble cross-section per 100 ml of glass volume is measured. See Table 10 in this catalogue.

7.6 Colouring

Variation of colouring between melts is generally within ± 10 nm.

On special request, we shall report the colouring or the transmission (including reflection losses) of the melt to be supplied by measuring spectral transmission.